{"description":"Trending threats, MITRE ATT\u0026CK coverage, and detection metadata — refreshed continuously.","feed_url":"https://feed.craftedsignal.io/tags/cve-2026-26143/","home_page_url":"https://feed.craftedsignal.io/","items":[{"_cs_actors":[],"_cs_cves":[{"cvss":7.8,"id":"CVE-2026-26143"}],"_cs_exploited":false,"_cs_products":[],"_cs_severities":["high"],"_cs_tags":["cve-2026-26143","powershell","input-validation","bypass-uac","windows"],"_cs_type":"advisory","_cs_vendors":[],"content_html":"\u003cp\u003eCVE-2026-26143 describes a vulnerability in Microsoft PowerShell stemming from improper input validation. This flaw could allow a local, unauthorized attacker to bypass security features implemented within PowerShell. The vulnerability has a CVSS v3.1 score of 7.8, indicating a high severity. Successful exploitation could lead to significant compromise of the affected system. The vulnerability was reported to Microsoft and assigned CVE-2026-26143. Defenders should prioritize patching affected systems to mitigate the risk. The affected versions of PowerShell are not explicitly stated in the source material, therefore all installations of PowerShell on Windows should be considered potentially vulnerable.\u003c/p\u003e\n\u003ch2 id=\"attack-chain\"\u003eAttack Chain\u003c/h2\u003e\n\u003col\u003e\n\u003cli\u003eAttacker gains local access to a Windows system. This could be through existing malware, physical access, or other initial access vectors.\u003c/li\u003e\n\u003cli\u003eAttacker crafts a malicious PowerShell command or script designed to exploit the input validation vulnerability (CVE-2026-26143).\u003c/li\u003e\n\u003cli\u003eThe attacker executes the malicious PowerShell command, bypassing intended security controls due to the input validation flaw.\u003c/li\u003e\n\u003cli\u003ePowerShell processes the crafted input, failing to properly sanitize or validate it.\u003c/li\u003e\n\u003cli\u003eThe bypassed security feature allows the attacker to perform actions that would normally be restricted, such as elevated privileges.\u003c/li\u003e\n\u003cli\u003eAttacker leverages the bypassed security feature to execute unauthorized code or modify system configurations.\u003c/li\u003e\n\u003cli\u003eThe attacker can now maintain persistence via registry keys (T1547.001) or scheduled tasks (T1053.005).\u003c/li\u003e\n\u003cli\u003eThe attacker achieves their objective, which could include data exfiltration, system compromise, or further lateral movement within the network.\u003c/li\u003e\n\u003c/ol\u003e\n\u003ch2 id=\"impact\"\u003eImpact\u003c/h2\u003e\n\u003cp\u003eSuccessful exploitation of CVE-2026-26143 can allow a local attacker to bypass security features within Microsoft PowerShell, potentially leading to arbitrary code execution with elevated privileges. This vulnerability could lead to a full system compromise. The number of potential victims is substantial, as PowerShell is a standard component of Windows operating systems. Systems lacking the security patch are vulnerable.\u003c/p\u003e\n\u003ch2 id=\"recommendation\"\u003eRecommendation\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003eApply the security update provided by Microsoft for CVE-2026-26143 to remediate the improper input validation vulnerability.\u003c/li\u003e\n\u003cli\u003eImplement the Sigma rule \u0026ldquo;Detect Suspicious PowerShell Input Validation Bypass\u0026rdquo; to identify potential exploitation attempts in your environment.\u003c/li\u003e\n\u003cli\u003eMonitor PowerShell execution logs for suspicious command-line arguments and script content, which could indicate an attempt to exploit this vulnerability.\u003c/li\u003e\n\u003cli\u003eRestrict local user access to reduce the attack surface and limit the potential for local exploitation.\u003c/li\u003e\n\u003cli\u003eEnable PowerShell logging and auditing to capture detailed information about PowerShell activity, which can aid in detecting and investigating suspicious behavior.\u003c/li\u003e\n\u003c/ul\u003e\n","date_modified":"2026-04-15T12:00:00Z","date_published":"2026-04-15T12:00:00Z","id":"/briefs/2026-04-powershell-input-validation-bypass/","summary":"An improper input validation vulnerability (CVE-2026-26143) in Microsoft PowerShell allows an unauthorized local attacker to bypass security features.","title":"Microsoft PowerShell Improper Input Validation Vulnerability (CVE-2026-26143)","url":"https://feed.craftedsignal.io/briefs/2026-04-powershell-input-validation-bypass/"}],"language":"en","title":"CraftedSignal Threat Feed — Cve-2026-26143","version":"https://jsonfeed.org/version/1.1"}